A computer virus is a program--a piece of executable code--that has the unique ability to replicate. Like biological viruses, computer viruses can spread quickly and are often difficult to eradicate. They can attach themselves to just about any type of file, and are spread by replicating and being sent from one individual to another. Simply having virus protection software on a computer system does not guarantee safety and security. Instead, protection and prevention is a team effort between the users and the anti-virus software. This article offers tips for virus protection.